1. Field
The present invention relates to aircraft components. More particularly, the invention relates to a composite and metal hybrid torque box and a method of constructing and attaching the hybrid torque box to a thrust reverser and an engine fan case.
2. Related Art
Aircraft equipped with under-wing engines generally contain thrust reverser units that are joined to an engine fan case via one or more torque boxes. The torque boxes may each provide mounting provisions for thrust reverser actuators and fixed structural connection between a hinge beam in a top half of the thrust reverser unit and a latch beam in the bottom half of the unit.
Torque boxes are traditionally made of metal and are expensive, heavy, and require multiple attached stiffening members to remain structurally effective. Composite torque boxes proposed to reduce weight have either been one-piece tubular structures or open-sectioned, composite, integrally-stiffened rings. The one-piece tubular structures typically require local composite ply build-ups or internal stiffening at critical load areas. Mounting actuator components and fittings onto the one-piece tubular structures is complicated due to inherently restrictive internal access. Open-sectioned, composite, integrally-stiffened rings mitigate the internal access issues of the one-piece tubular structures, but are costly, require intricate fabrication details, are difficult to inspect, and sacrifice some torsional structural efficiency compared to one-piece tubular structures. Additionally, these open-sectioned rings generally require a multitude of molds to define various stiffening details.
Accordingly, there is a need for torque boxes that overcome the limitations of the prior art.